Hot-fillable plastic container with flexible base feature

ABSTRACT

A base for a plastic container including an outer support portion; a structured formation ring including a plurality of sequential formations; an inner inversion portion disposed radially inwardly of the structured formation ring; and a central portion. In an embodiment, the sequential formations are disposed in a substantially ring-like configuration and at least the inner inversion portion is configured to flex in response to internal vacuum forces associated with said container.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation application to U.S. patentapplication Ser. No. 12/646,647, filed Dec. 29, 2009, which claimspriority to U.S. Provisional Application No. 61/141,812, filed Dec. 31,2008, the applications are fully incorporated herein by reference.

TECHNICAL FIELD

The present invention relates generally to the field of plasticcontainers, particularly plastic containers having an improved baseportion design to accommodate hot-fill conditions.

BACKGROUND

Today, a great number of plastic containers are filled with liquids andother contents at elevated temperatures. However, as the product withinthe container cools, the volume taken up by the product decreases,inducing a partial vacuum that exerts an inward force on the walls ofthe container. Containers that are intended to be filled by a “hot-fill”process are commonly referred to as hot-fill containers. The design ofhot-fill containers is influenced by, among other things, a desire toaccount for anticipated content cooling/shrinkage and associated forces.

SUMMARY

A base for a plastic container including an outer support portion; astructured formation ring including a plurality of sequentialformations; an inner inversion portion disposed radially inwardly of thestructured formation ring; and a central portion. In an embodiment, thesequential formations are disposed in a substantially ring-likeconfiguration and at least the inner inversion portion is configured toflex in response to internal vacuum forces associated with saidcontainer.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of example,with reference to the accompanying drawings, wherein:

FIG. 1 generally illustrates a plastic container according to anembodiment of the invention;

FIG. 2 is a bottom plan view of a container base portion according to anembodiment of the invention;

FIG. 3 is front sectional view of a portion of a container base portionaccording to an embodiment of the invention;

FIG. 4 is a front partial perspective view of a container base portionaccording to an embodiment of the invention;

FIG. 5 is a side view outline of a container base portion according toan embodiment of the invention, shown prior to hot-filling;

FIG. 6 is a side view outline of a container base portion of the typeillustrated in FIG. 5, shown after hot-filling (i.e., after cooling);

FIG. 7 is a bottom plan view of a container base portion according toanother embodiment of the invention;

FIG. 8 is a side view outline of a container base portion according toanother embodiment of the invention, shown prior to hot-filling;

FIG. 9 is a side view outline of a container base portion of the typeillustrated in FIG. 8, shown after hot-filling (i.e., after cooling);

FIG. 10 is a side view outline of a container base portion according toyet another embodiment of the invention, shown prior to hot-filling; and

FIG. 11 is a side view outline of a container base portion of the typeillustrated in FIG. 10, shown after hot-filling (i.e., after cooling).

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments of the presentinvention, examples of which are described herein and illustrated in theaccompanying drawings. While the invention will be described inconjunction with embodiments, it will be understood that they are notintended to limit the invention to these embodiments. On the contrary,the invention is intended to cover alternatives, modifications andequivalents, which may be included within the spirit and scope of theinvention as defined by the appended claims.

FIG. 1 generally illustrates a plastic container 10 having a verticalcenterline CL and including a base portion 20 according to an embodimentof the present invention. The container 10, and consequently the base20, may be comprised of a polymer, such as without limitationpolyethylene terephthalate (PET), and may be biaxially oriented. A planview of the base portion 20 is generally shown in FIG. 2. The inventionis not, however, limited to the type or style of container shown, andvarious other sizes and configurations (such as, for example and withoutlimitation, the configuration generally illustrated in FIG. 7) may comewithin the scope and spirit of the present invention.

The base portion 20 of the illustrated embodiment includes an outersupport portion (which may take the form of an annular support ring 30);a first inversion portion (e.g., first inversion ring 40); a flat (orstep portion) 50; a structured formation ring 60 (also referred to as a“zipper ring”); a second inversion portion 70; and a central portion 80.As generally illustrated, central portion 80 may include a domed orelevated portion, including those provided in connection with variousconventional containers. Further, as generally illustrated, the baseportion 20 may also include one or more structural reinforcingformations 90.

In embodiments, the flat (or step portion) 50 may be provided between anouter support ring 30 and a zipper ring, and may further be providedbetween a first inversion portion 40 (which may be an angledsegment/portion) and a zipper ring 60. The flat (or step portion) 50 maybe substantially flat, and for some embodiments may be generallyperpendicular to the vertical centerline CL. However, some degree ofangularity (from perpendicular) with the flat 50 may also be providedwith some embodiments.

The outer support portion, which may comprise an annular support ring30, can be configured to support the container 10 on a surface. Asperhaps better illustrated in FIGS. 5 and 6, the first inversion portionmay comprise an angled segment, i.e., angled with respect to thevertical centerline CL of the container.

In embodiments of the invention, the structural reinforcing formationsmay include a plurality of radially extending ribs 90—the size and/orshape of which may be varied. In the illustrated embodiment threeradially extending ribs 90 are shown disposed at 120 degree intervalsabout the vertical centerline CL of the container 10. Additionally, thestructural reinforcing formations that may be provided can be configuredto extend inwardly (e.g., inward recesses or slits) and/or outwardlywith respect to adjacent wall portions of the container base portion 20.However, it is noted that the invention is not limited to theillustrated structural reinforcing formation, and various otherformations known to those of skill in the art may be employed inaddition to, or in lieu of, the depicted formations.

FIG. 3 generally depicts a front sectional view of a portion of acontainer base portion 20 according to an embodiment of the invention.The container illustrated in FIG. 3 being shown in an unfilledcondition. A front partial perspective view of a container base portionof the type shown in FIG. 3 is illustrated in FIG. 4. As generallyillustrated in FIG. 4, structural formation ring (or zipper ring) 60 maycomprise a plurality of sequential formations 110 (also referred to as“teeth”). In an embodiment, sequential formations 110 may extendinwardly relative to immediately adjacent portions of the base. Forother embodiments, sequential formations 110 may extend outwardly withrespect to immediately adjacent portions of the base. As illustrated,adjacent teeth 110 (which are shown in FIG. 2 as somewhat“diamond”-shaped formations) may be separated, in whole or insubstantial part, by intermediate surface portions 100 providedtherebetween. While “diamond”-shaped teeth 110 are illustrated inconnection with certain embodiments, other constructions that mayprovide the intended functionality (such as, without limitation,constructions involving a plurality of teeth “triangular”-shaped teeth)may instead be provided or, for some embodiments, differingconfigurations of teeth may be interspersed in patterns (e.g.,alternating). In an embodiment intermediate surface portions 100 maycomprise generally planar portions or segments. Additionally, for someembodiments, the sequential formations 110 of the zipper ring 60 may beinterrupted by one or more interruption formations, e.g., lugs ororientation formations. The zipper ring 60—which can comprise an annularsegment including a plurality of alternating teeth 110 and intermediatesurface portions 100—can be configured to serve as a hinge point, andcan distribute stress concentration forces (created from a coolingvacuum) substantially evenly around the perimeter of the support ring30. For embodiments such a configuration can alleviate potential forcreasing and permit more uniform displacement of the support ring 30under a vacuum. Moreover, with reference to the illustrated embodiment,a flat 50 may surround the zipper ring 60 and may additionally serve asan outer inversion ring—which can work in conjunction with the zipperring 60 to permit a greater displacement of the base portion 20 whenunder vacuum pressure.

FIG. 5 generally illustrates a side view outline of a container baseportion 20 according to an embodiment of the invention, shown prior tohot-filling. FIG. 6 generally illustrates the base portion 20 shown inFIG. 5, after hot-filling—i.e., after the contents of the container 10have cooled and the container has experienced associated vacuum forces.As generally illustrated in FIG. 5, in the pre-hot-fill condition, thezipper ring 60 may extend downwardly to a level that is at or about thelevel of the support ring 30. Moreover, for some embodiments, the zipperring 60 associated with an unfilled container 10 may extend below thelevel of the support ring 30.

Various transportation techniques may be used to convey containers thatare provided in accordance with the teachings of the invention. Forexample, without limitation, various table conveyance and/orneck-directed carrying options (including those that utilize airconveyance) may be employed for embodiments of the invention, includingthose in which the zipper ring 60 of an unfilled container extends belowthe level of the support ring 30.

With continuing reference to FIG. 5, a distance D is generallyillustrated. Distance D represents a difference in height between theflat 50 and the lowermost portion of support ring 30. For someembodiments, without limitation, distance D may be in the order of 0.065to 0.010 inches. Further, for some other embodiments where containerbase portion 20 does not include an outer inversion portion, withoutlimitation, distance D may be in the order of 0.065 to 0.000 inches.

By way of example, without limitation and depending, in part on theoverall total package weight, for embodiments of the invention—(a) thewall thickness of the zipper ring 60 may range from 0.008 to 0.030inches; and (b) the wall thickness of the first (outer) inversion ring40 may range from 0.006 to 0.035 inches.

Container 10 is generally adapted to be hot-filled with liquid having atemperature of between 140° and 210° Fahrenheit. By way of example,without limitation, for embodiments of the invention, container 10 maybe filled at between 160° and 190° Fahrenheit.

A plan view of another embodiment of a base portion 20′ according toteachings of this disclosure is generally shown in FIG. 7. The baseportion 20′ of the illustrated embodiment includes an outer supportportion (which may take the form of an annular support ring 30′); afirst inversion portion (e.g., first inversion ring 40′); a flat (orstep portion) 50′; a structured formation ring 60′ (also referred to asa “zipper ring”); a second inversion portion 70′; and a central portion80′. As generally illustrated, central portion 80′ may include a domedor elevated portion, including those provided in connection with variousconventional containers. Further, as generally illustrated, the baseportion 20′ may also include one or more structural reinforcingformations 90′. It is additionally noted that the central portion 80′may be configured in various other forms. For instance, and withoutlimitation, central portion 80′ may instead be configured as generallyillustrated in connection with the embodiment of central portion 80shown in FIG. 2.

FIG. 8 generally illustrates a side view outline of a container baseportion 20A according to an embodiment of the invention, shown prior tohot-filling. FIG. 9 generally illustrates the base portion 20A shown inFIG. 8, after hot-filling—i.e., after the contents of the container havecooled and the container has experienced associated vacuum forces. Asgenerally illustrated in FIG. 8, in the pre-hot-fill condition, thezipper ring 60′ may extend downwardly to a level that is perceptivelylower than, or beneath, the level of the support ring 30′. FIG. 9illustrates a configuration in which, after the effect of vacuum forces,the support ring 30′ then transitions to a level that is below orbeneath the associated zipper ring. FIG. 9 also depicts some angulardimensions that may be associated with embodiments of the disclosure.For example, illustrated angle α may be 8.0°±5.0°; illustrated angle βmay be 14.0°±5.0°; and illustrated angle γ may be 55°±25°.

FIG. 10 generally illustrates a side view outline of a container baseportion 20B according to another embodiment of the invention, shownprior to hot-filling. FIG. 11 generally illustrates the base portion 20Bshown in FIG. 10, after hot-filling—i.e., after the contents of thecontainer have cooled and the container has experienced associatedvacuum forces. As also generally illustrated in FIG. 10, in thepre-hot-fill condition, the zipper ring 60″ may extend downwardly to alevel that is lower than, or beneath, the level of the support ring 30″.FIG. 11 illustrates a configuration in which the zipper ring 60″, afterthe effect of vacuum forces, then extends above the level of supportring 30″. FIG. 11 also expressly depicts several angular dimensions,angles α and β, that may be associated with embodiments of thedisclosure. In embodiments, the illustrated angles associated with FIG.11 may be the same or substantially equivalent to the angular rangesdisclosed in connection with FIG. 9, that is, angle α shown in FIG. 11may also be 8.0°±5.0°, and angle β may also be 14.0°±5.0°.

The foregoing descriptions of specific embodiments of the presentinvention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and various modifications andvariations are possible in light of the above teaching. The embodimentswere chosen and described in order to explain the principles of theinvention and its practical application, to thereby enable othersskilled in the art to utilize the invention and various embodiments withvarious modifications as are suited to the particular use contemplated.It is intended that the scope of the invention be defined by the claimsappended hereto and their equivalents.

What is claimed is:
 1. A base for a plastic container comprising: anouter support portion comprising an annular support ring; a structuredformation ring including a plurality of sequential formations, thesequential formations including a plurality of teeth disposed in asubstantially ring-like configuration; a flat or step portion providedbetween the outer support portion and the structured formation ring; aninner inversion portion disposed radially inwardly of the structuredformation ring; and a central portion including one or more structuralreinforcing formations; wherein at least the inner inversion portion isconfigured to flex in response to internal vacuum forces associated withsaid container.
 2. The base of claim 1, wherein the central portionincludes a plurality of radially extending ribs.
 3. The base of claim 1,wherein an intermediate surface portion is provided at least in partbetween adjacent sequential formations.
 4. The base of claim 1, whereinthe plurality of sequential formations comprises an annular segmentincluding a plurality of alternating teeth and intermediate surfaceportions.